Archive for December 2012 (11 posts)

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During the Civil War, cartographers invented new techniques to map the country and the conflict more accurately than ever before in the nation’s history. Since then, cartographic technology has evolved in ways never imagined, but many basic elements of mapmaking remain the same. The following is an article, written by Jacqueline V. Nolan and Edward J. Redmond of the Library’s Geography and Map Division, that is featured in the November-December 2012 issue of the Library’s new magazine, LCM, and highlightsprogress in cartography since the Civil War.

A sketch map of the battlefield of Gettysburg, 1863, by Jedidiah Hotchkiss combined with U.S. Geological Survey’s satellite-derived map with attributes from the National Hydrography dataset

Mapmaking has been revolutionized since the Civil War. Comparatively speaking, creating a map using modern technologies little resembles yesteryear’s methodology. Yet, many consistencies in mapping prevail from one era to the next. The basic elements of map production still consist of determining geographic coordinates and reference points, construction of projections, design, compilation, drafting and reproduction.

During the Civil War era, the production of a finished map was a protracted and labor-intensive process that involved a variety of skills and crafts. It began with a land survey or field reconnaissance by a military topographer—often on horseback—with sketchbook in hand. Rivers, roads and significant landscape features were rapidly drawn in pencil on pages marked with grid lines. Direction was determined by compass bearings, and distance was tracked by pacing on foot or horseback. Data from these field sketches were later transferred to larger sheets notated with geographic coordinates to produce a composite manuscript map of an area or region at a particular scale.

If a map was to be reproduced for wider dissemination, copies could be furnished in a variety of formats. Various photographic methods were devised during the war to reproduce manuscript field surveys quickly, in limited numbers for field commanders. Woodcut engraving was favored by newspapers, which published maps almost daily to help war families locate the remote places described in the letters they received from their loved ones at the front. Official and commercial maps were engraved or lithographed, and then hand-colored. Each of these processes required trained craftsmen as well as specialized tools and equipment. The copperplate engravers who worked for the U.S. Coast and Geodetic Survey, for example, were primarily German craftsmen recruited especially for the detailed engraving required by that agency.

Current trends in mapping allow for multiple layers of data to be combined by one cartographer using Geographic Information Systems (GIS) software on a desktop computer. GIS has become a useful tool for research using spatial data analysis and is being applied to many fields of study, wherever geography can be modeled.

U.S. Geological Survey’s satellite- derived map of Gettysburg, 2007

U.S. Geological Survey’s satellite- derived map of Gettysburg, 2007 Original sketch of the Battle of Gettysburg by Jedidiah Hotchkiss, 1863

Creating a map using GIS is also a layered process. Using multiple sources of data, such as field data, research statistics, real-time data, and so on, information can be overlaid on a base map representing a geographic area of interest such as a Civil War battle site. Base layers may be characterized as either a pixilated, raster format, derived from remote-sensing imagery, or as a vector file, which depicts geography as points, lines and polygons.

Map specifications such as projection, scale, and key details are determined in this initial phase. Data is standardized to ensure attribute- matching with the base layer prior to performing data analysis.

GIS software packages include toolkits containing many devices for analysis and editing. Metadata is compiled to document specific information about the GIS project, such as source data, attribute definitions, or algorithms used for statistical computations. Analysis is the primary end-product of a GIS project, though a cartographic rendering may be created such as a paper map, a web-based application for visual interpretation on a computer screen, or applications software for display on mobile devices (apps).

I remember the moment I found out that jolly old St. Nick was more an idea than a physical person shimmying down a chimney to deposit presents underneath the tree. First clue, we didn’t have a fireplace. I can’t remember exactly how old I was, probably elementary school age. The night before Christmas I could […]

Today marks 19 years since the passing of one of the world’s great management thinkers—W. Edwards Deming. After World War II, the U.S. did something remarkable in the history of war – it helped its friends and even its former foes get back on their feet economically. In Europe, that was accomplished through the Marshall […]

(The Maya calendar has generated a lot of buzz about the impending end of the world as we know it, on Dec. 21, 2012. The following is an article written by colleague Audrey Fischer from the November-December 2012 issue of the Library’s new magazine, LCM, highlighting what’s “trending” in the news, on the web and […]

The following is a guest post by Jason Steinhauer, program specialist in the Library’s John W. Kluge Center, as part of the Inquiring Minds series. The revolutionary wave of demonstrations, protests and wars known collectively as the Arab Spring has spanned Algeria to Oman, covering a distance of 3,400 miles and toppling regimes that governed […]

In November, Library bloggers presented a feast of posts, sure to whet a variety of appetites. Here are a few selections. In the Muse: Performing Arts Blog 1707: A Year That Will Resonate with Handel Lovers 1707 was a good year for Handel. The Signal: Digital Preservation When Data Loss is Personal Leslie Johnston talks […]

This Saturday marks my return to the Kennedy Center stage singing as part of The Washington Chorus in our annual series of holiday concerts. I’ve been a part of this large ensemble for about three years now, and our December concerts are some of our most popular. There’s nothing like singing yuletide carols to get […]

The collections of the Library of Congress are vast and varied. And, what better way to get to know them but through our many wonderful curators. In this edition of “Curator’s Picks,” Sara Duke, curator of popular and applied graphic art in the Library’s Prints and Photographs Division, and reference librarian Megan Halsband of the […]

What if Abraham Lincoln recorded his innermost thoughts as he moved toward the realization that he must end slavery? What if he lost that diary, but a recently discovered letter suggests that the diary is still out there? Such is the premise of “The Lincoln Letter” (Tor/Forge, 2012) by William Martin, his latest mystery novel […]

Pianist Dave Brubeck, one of America’s all-time greats in the field of jazz — and a seminal force in making jazz popular in the U.S. and throughout the world — died today, just shy of his 92nd birthday. The Librarian of Congress bestowed the Library’s “Living Legend” award on Brubeck in 2003, and it […]

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